Display Device Common Electrode Segmentation for Noise Reduction
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Solution Overview
Problem
Display devices face challenges in simultaneously performing sensing functions like touch recognition and light detection while driving the display, due to noise interference from voltage variations caused by signal application, which complicates the arrangement of sensing configurations on the display panel.
Innovation Solution
The implementation of a display device with photo transistors in subpixels, read-out transistors, and a specific common electrode configuration that allows for the accumulation and detection of electrical charges from touch or light, enabling simultaneous sensing and display driving with reduced noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photo transistors and sensing configurations are arranged on the display panel, then sensing capability is improved, but device complexity and design difficulty increase
Solution Approach 1:
The patent implements multi-functionality by enabling subpixels to serve dual purposes: display function through driving transistors and sensing function through photo transistors. The same subpixel structure and electrode arrangements are used for both displaying images and detecting touch inputs or external light, thereby improving sensing capability without proportionally increasing device complexity
Solution Approach 2:
The patent merges the display and sensing functions into a unified structure. Photo transistors are integrated within subpixels alongside driving transistors, and common electrodes serve both display and sensing purposes. This consolidation allows sensing configurations to be arranged within the existing display framework, reducing overall design complexity
2Productivity
If display driving signals are applied to the display panel, then display function is improved, but noise interference in sensing signals increases
Solution Approach 1:
The patent segments the common electrode into multiple independent common electrode lines (first common electrode line, second common electrode line, etc.). Each line can be independently controlled and timed, allowing the system to apply display driving signals to some lines while maintaining or adjusting voltage on other lines during sensing periods. This segmentation enables temporal and spatial separation of display and sensing operations, reducing noise interference in sensing signals
Solution Approach 2:
The patent implements periodic action by alternating between display driving periods and sensing periods through controlled voltage application to common electrode lines. During sensing periods, voltage is maintained or adjusted on specific common electrode lines to minimize interference, while during display periods, full display driving signals are applied. This periodic switching allows both display function and sensing accuracy to be optimized at different times
3Area of stationary object
If common electrode is arranged overlapping both data line and read-out line, then electrode coverage is improved, but noise coupling between sensing signal and data signal increases
Solution Approach 1:
The patent segments the common electrode into multiple distinct common electrode lines, where each line overlaps with specific signal lines. The first common electrode line overlaps with read-out lines, while the second common electrode line overlaps with data lines. This segmentation allows independent voltage control for each electrode line, enabling the system to maintain voltage on data-line overlapping electrodes during sensing to reduce noise coupling, while preserving full coverage benefits
Solution Approach 2:
The patent applies local quality by assigning different voltage control characteristics to different segments of the common electrode structure. Electrode segments overlapping with read-out lines receive different voltage control compared to segments overlapping with data lines. This localized differentiation allows optimal noise reduction at sensing-critical locations while maintaining overall electrode coverage for display performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for effective sensing of user input and external light during display operation, improving sensing performance by minimizing noise in the sensing signal and enabling a more integrated and efficient design for display devices.
Implementation Method 1
a plurality of photo transistors disposed in at least one subpixel of the plurality of subpixels, controlled by a photo control signal applied to a photo control line
Implementation Method 2
a first common electrode partially overlapping the read-out line, and a second common electrode partially overlapping the data line and being separated from the first common electrode
Data Source
AI summary
A display device is capable of sensing a user's touching or inputting by a laser pointer on a display panel, by means of arranging a photo transistor in some pixels of the display panel to sense off-current of the photo transistor according to a change in the quantity of external light. In addition, a common electrode overlapping a data line is arranged separately from a common electrode overlapping a read-out line from which a sensing signal is detected, thereby improving the sensing performance carried out simultaneously with the display driving, owing to reduced influence of noise caused by the display driving to the sensing signal.